refactor: adapt Button fields to the cce-ui Phase 5 migration

Button::new now returns Adapted<Button>; concrete-typed fields become
Adapted<Button>. Construction sites, builder chains, and method calls
are unchanged (Deref + Element forwards + mirrored builders).

Co-Authored-By: Claude Fable 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01LkfJazPs9bRchkcozmxXCX

 src/main.rs | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/main.rs b/src/main.rs
index 8ed832e..e3f63c8 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -57,9 +57,9 @@ struct AuthenticatorApp {
     font_system: FontSystem,
     bg: ContentBg,
     password_box: TextBox,
-    verify_btn: Button,
-    cancel_btn: Button,
-    fingerprint_btn: Button,
+    verify_btn: cce_ui::widget::Adapted<cce_ui::widget::Button>,
+    cancel_btn: cce_ui::widget::Adapted<cce_ui::widget::Button>,
+    fingerprint_btn: cce_ui::widget::Adapted<cce_ui::widget::Button>,
     
     status_msg: String,
     status_is_error: bool,